The present invention relates to non-contact methods for measuring quantity of sebum or oil on skin or other substrates. While measurement can be done in vivo or ex vivo, the technique is preferred for use in vivo because of the ability to measure formation of oil on the skin in real time.
Methods of analyzing the quantity of sebum or oil produced on substrate/surfaces using so-called contact techniques are known. Generally such contact methods mean that the measurement involves contact with the surfaces where the sebum/oil is being measured. Since the sebum or oil is generally sampled and then measured, it is difficult or impossible to monitor changes in real time, i.e., as they are occurring. For example, xe2x80x9cIn-vivo infrared analysis of the recovery of sebaceous lipids after dilapidationxe2x80x9d, J. Invest. Dermatology, 112(4), 779 (1999), N. Kolliar et al. describe an ATR-FTIR method for sebum detection using a fiber optic probe attachment. This is a contact method involving collection and transfer of sebum onto an ATR (attenuated total internal reflection device) crystal. Other contact methods include use of sebutape, use of a sebumeter and lipid extraction using solvents.
JP 09292214 (assigned to Sekisui Chemical) discloses a non-contact ultrasound method for measuring skin sebum. Here however, the ultrasound measures only the thickness of the fat layer and not actual amounts of sebum produced.
Other contact methods are also disclosed in the following references.
In JP 05060686, sebum is collected from the surface using a plate and then an IR spectrum is obtained using ATR device.
In JP 02220630, sebum quantity is measured using IR rays to detect reflected light from sebum collecting surface.
In U.S. Pat. No. 5,094,248 to Kawam, sebum is collected onto a hydrophilic open celled microporous polymeric film by patching to skin, and the amount of sebum collected is measured against a selected background by optical methods.
In U.S. Pat. No. 4,224,950 to Bore et al., sebum is collected onto a frosted glass plate and quantified using optional methods.
In U.S. Pat. No. 4,313,393 to Barbuscio et al., sebum is collected using an oil absorbent material, and the amount collected is quantified using a dye.
In WO 96/25884 (assigned to Courage and Khazaka), sebum secretion on skin is measured using a microporous water repellent, sebum absorbing opaque foil which absorbs sebum and changes in transparency.
None of these methods are true xe2x80x9cnon-contactxe2x80x9d methods and, therefore, they do not allow monitoring sebum levels in vivo in real time.
Unexpectedly, applicants have discovered that it is possible to measure quantity of sebum or oil in vivo using non-contact technique. This also allows real time measurement.
The present invention relates to a non-contact (non-invasive) method for measuring quantity of sebum or oil on skin or other substrate. Because the measurements are truly non-contact, they can be made in real time on the same sites for any desired length of time.
The present invention discloses one specific embodiment for non-contact measurement. A second embodiment is disclosed in a separate application filed on same day as the subject application.
In the embodiment of the present invention, an amount of sebum (or oil) is measured by choosing a desired spot on the subject""s body; optionally cleansing the spot by a mild wash using a cleanser or wipe; applying a desired amount of fluorescent dye (e.g., octadecyl fluorescent or xe2x80x9cODFxe2x80x9d, a highly lipophilic fluorescent dye) to the spot; illuminating the spot at the excitation wavelength of the fluorescent dye (470 nm for ODF); and acquiring an image at the desired wavelength of the dye (525-540 nm for ODF). Alternatively fluorescence spectral measurement (e.g., in steps (4) and (5) noted below) can be acquired from the spot at the appropriate excitation wavelength using, for example, a fiber optic probe assembly attached to a spectrophotometer.
More specifically, the invention comprises a non-contact process or method for measuring sebum or oil from skin or other substrate comprising:
(1) choosing a desired spot (e.g., on the forehead), typically about 1-2 cm in diameter (could be as large as the entire forehead), on the body of a subject;
(2) optionally cleansing said spot using typically mild cleansing wash, facial wash or alcoholic wipes in an amount adequate to remove all or part of sebum or oil;
(3) applying lipophilic fluorescent dye, which exhibits concentration dependent self-quenching, at levels just above its self quenching concentration (5 to 10 xcexcg/cm2 for ODF) to the spot where sebum oil is to be measured;
(4) illuminating the spot on said subject at the excitation wavelength of the fluorescent dye (e.g., 450-500 nm for ODF); and
(5) collecting fluorescent emission at desired wavelength of the dye (e.g., 525-560 for ODF) using for example a camera and suitable image acquisition system.
In an alternative embodiment, the fluorescence spectra of the dye on the spot may be recorded by using a fiber optic probe attached to a spectrophotometer. The fiber optic probe delivers the illumination from the light source to the spot (again at 450-500 nm for ODF) and also collects the fluorescence from the spot (e.g., at 525-560 nm for ODF)); and
(6) quantifying data from acquired image by analyzing fluorescence intensity in the images or spectra and converting to amount of sebum or oil increased using appropriate calibrations determined in separate experiments.
Images or spectra are acquired at desired time intervals and converted to oil or sebum amounts using step (6) in the real time, normally in-vivo application of the method. Often it is desired to measure sebum/oil increase from a point where there is little or no previous oil. In this case, the measured skin spot would be cleansed at the beginning (step (2)), dye applied (step (3)) and measurements taken.
However, it should be understood that the measurements can be taken to measure oil/sebum increase at any time, not just the beginning. Thus, at a later point for example, after there has already been sebum/oil collection, it is possible to avoid step (2), apply dye and measure how much oil/sebum has been collected from that later measurement point.
Also, even if measured from beginning, one can skip cleansing step. However, it will be appreciated, that a baseline measurement of oil/sebum should be taken to quantitate.